Types of Telescopes
Telescope Types Explained
There are many different types of telescopes available for those interested in exploring the night sky. Telescopes come in a variety of designs, some of which have been around since the 1600s.
The first practical telescope is generally traced to the Netherlands in 1608, when spectacle maker Hans Lippershey submitted a patent application for a refracting design. Soon after, Galileo improved the design and applied it to astronomy.
The three main types of telescopes are refracting telescopes, reflecting telescopes, and catadioptric telescopes. Each type has many variations and hybrid designs.
I consider a Dobsonian reflector to be the best telescope type for most visual beginners because it combines simplicity, useful aperture, and affordability. For beginner deep-sky astrophotography, a compact apochromatic refractor is usually the easier place to start.
A Dobsonian is a Newtonian reflector on a simple, stable alt-azimuth mount rather than a separate optical design. An 8-inch model is excellent for exploring the sky visually, while a small refractor on an accurate tracking mount is a forgiving setup for photographing large deep-sky objects.
Setting up my Schmidt-Cassegrain telescope for a night of astrophotography.
If you are a beginner and looking to purchase your first telescope, it is recommended that you have a clear vision of what you want to use it for (e.g., visual, photography, planetary, deep-sky, etc.), your available budget, and the level of complexity you want to take on for your equipment set-up.
Related Post: How to Use Your First Telescope
The main goals of an astronomical telescope are to gather light and resolve fine detail. People often focus on magnification, but useful magnification is limited by the telescope’s aperture, optical quality, and atmospheric seeing.
When choosing a telescope, many different characteristics come into play, but arguably, the two most important factors will be your desired focal length and aperture.
Focal length helps determine image scale and field of view, but it does not set visual magnification by itself. Magnification equals the telescope’s focal length divided by the eyepiece focal length. The aperture determines how much light the telescope gathers and how much fine detail it can theoretically resolve.
An 8-inch Dobsonian Telescope with a focal length of 1200mm at F/5.9.
Refractor vs. Reflector vs. Dobsonian
| Telescope type | How it works | Best suited to | Main trade-off |
|---|---|---|---|
| Refractor | Front objective lens | Low-maintenance visual use and wide-field imaging | Costs more per inch of aperture |
| Newtonian reflector | Concave primary mirror and flat secondary mirror | Large aperture at a lower price; visual use or imaging when properly mounted | Requires occasional collimation |
| Dobsonian | Newtonian optical tube on a manual alt-azimuth base | Beginner visual astronomy and maximum aperture for the money | Bulky at larger sizes and not designed for long-exposure imaging |
| Catadioptric | Mirrors plus a corrector lens | Compact lunar, planetary, and small-target observing or imaging | Higher cost, longer cool-down, and a narrower field |
What Is the Best Telescope?
I am a full-time astrophotographer, and I have used many different types of telescopes to both view and photograph the wonders of the night sky. Rather than treating one model as universally best, the advice below is based on what each design does well in the field.
Keep in mind that this is from the perspective of a backyard stargazer who primarily focuses on deep-sky astrophotography but also likes to visit a star party or two for the visual experience. The following suggestions are for those looking to view objects in space through a telescope.
If you are primarily interested in capturing images through your telescope, check out my list of best astrophotography telescopes.
Which telescope is best for seeing planets?
If you are interested in viewing the solar system planets up close, you’ll want good optics, adequate aperture, and steady atmospheric conditions. A 6- to 8-inch Dobsonian is a great choice; larger 10- or 12-inch models can reveal more detail when they are properly cooled and the seeing supports it.
If you want to photograph planets in detail, a large-aperture, long-focal-length telescope like a Schmidt-Cassegrain is tough to beat. A motorized tracking mount keeps the planet on the camera sensor while you record high-frame-rate video.
What is considered the best telescope?
Determining the “best” telescope depends on your personal observing preferences, goals, and budget. However, when people ask me this, I often suggest an 8″ Dobsonian telescope because it offers one of the best user experiences for the price.
Reflector telescopes offer larger apertures for the price, resulting in deeper, more detailed views of the planets, the moon, and even deep-sky objects such as galaxies and nebulae. See my review of the Apertura AD8 Dobsonian Reflector as a fantastic example of this type of telescope.
Which is the best telescope to view galaxies?
Because most galaxies appear small and dim from our vantage point on Earth, dark skies and sufficient aperture matter more than extreme magnification. Newtonian reflectors are a great choice for those on a budget and can reveal detail in the brightest galaxies under transparent skies.
The largest galaxies can be seen in almost any telescope, under the right conditions. For example, my first successful photograph of the Andromeda Galaxy was captured using a compact refractor telescope with an 80mm aperture. However, viewing galaxies through the eyepiece of a telescope like this is not ideal.
If you are looking for the ultimate viewing experience, a Dobsonian telescope with an aperture of 12″ or more will show fainter objects than most other telescopes. The telescope shown below (Sky-Watcher FlexTube 350P) is the biggest visual telescope I have ever used, and I was able to see more galaxies in this telescope than any other model I own.
A 14″ Dobsonian telescope for viewing galaxies.
Which Telescope Is Best for Seeing Saturn’s Rings?
Witnessing Saturn’s iconic rings through a telescope is one of the most memorable astronomy experiences one can have. Even a quality 70- to 90mm telescope can separate the rings from the planet, while a 150mm (6-inch) or larger instrument can show finer ring detail when the atmosphere is steady.
Start with a low-power eyepiece, center Saturn, and increase magnification gradually. A motorized tracking mount is convenient at high power, but it is not required to see the rings.
In the video below, you can watch me photograph the planet Saturn through my Celestron Edge HD 11 telescope in the backyard.
What is the best telescope for moon gazing?
The moon is probably the easiest thing to see through a telescope, and it never disappoints. With its captivating craters and various moon phases, viewing the lunar landscape up close is a favorite target for many stargazers.
Almost any astronomical telescope is suitable for viewing the moon. A well-corrected refractor can provide especially crisp, high-contrast views, and a 100mm apochromatic refractor will reveal an impressive amount of lunar detail.
If detailed lunar surface photos are your goal, a larger Newtonian reflector or Schmidt-Cassegrain can resolve smaller features when the seeing is steady. You do not need a 10-inch telescope to enjoy the moon, but added aperture creates more potential resolution.
The full moon captured through a 150mm refractor telescope.
Key Telescope Specifications:
- Aperture (Light Gathering and Resolution)
- Focal Length (Image Scale, Field of View, and Eyepiece Magnification)
- Focal Ratio (Focal Length Divided by Aperture)
The aperture controls light-gathering ability and potential resolution. Focal length influences image scale and field of view, while focal ratio is especially important in astrophotography because it affects exposure time and how demanding the optics are at the edge of the field.
Eyepieces determine visual magnification: divide the telescope focal length by the eyepiece focal length. For example, a 1200mm telescope with a 25mm eyepiece provides 48X, while a 10mm eyepiece provides 120X. A longer-focal-length eyepiece is usually best for finding objects and viewing large targets; a shorter-focal-length eyepiece is useful for the moon and planets when conditions allow.
How Much Aperture Do You Need?
For portable visual observing, a 70- to 100mm refractor can provide excellent views of the moon, planets, double stars, and bright star clusters. A 130- to 200mm reflector gathers substantially more light for nebulae, globular clusters, and galaxies while remaining manageable for many beginners. Larger apertures reveal fainter objects, but only if you can comfortably transport, cool, and set up the telescope. The best value is often the largest telescope you will use regularly, not the largest one you can afford.
Choose a Telescope for Your Observing Location
In a light-polluted city, prioritize the moon, planets, double stars, and bright clusters; a convenient refractor, Maksutov-Cassegrain, or compact GoTo telescope can work well. For faint nebulae and galaxies, traveling to darker skies often improves the view more than adding a small amount of aperture. If you must carry equipment down stairs or drive to observe, portability should be treated as a core specification. At a dark rural site, a larger Dobsonian makes excellent use of the better sky.
These factors create a unique viewing experience based on your goals. Below are the three main optical categories, including the advantages, disadvantages, and a few examples of telescopes I have used.
As an astrophotographer first, a visual astronomer second, I understand the confusion that some folks have about choosing their first telescope. Unfortunately, there is no one-size-fits-all telescope for great visual observations, and practical astrophotography too.
In the video below, I discuss the type of telescope I would recommend for a complete beginner (a manual Dobsonian reflector).
Manual vs. Computerized GoTo Telescopes
A manual Dobsonian puts most of your budget into aperture and is quick to set up, but you must locate and track objects yourself. A computerized GoTo mount, such as the one included with the Celestron NexStar series, can locate targets after an alignment routine and keep them centered for visual observing. GoTo does not improve the telescope’s optics, and it adds cost, power requirements, motors, and setup steps.
GoTo can be especially helpful under light pollution, where fewer guide stars are visible, or when sharing views with a group. However, a GoTo alt-azimuth mount is not automatically suitable for long-exposure deep-sky photography because field rotation remains an issue. That work normally calls for an equatorial tracking mount. Eyepieces, filters, finders, focusers, and many optical tubes can be upgraded over time, but converting a basic manual Dobsonian into a full imaging system is rarely economical.
Refractor Telescopes
A refractor telescope collects and focuses light with a glass objective lens at the front of a closed tube. The objective usually contains two or more lens elements that bend, or refract, incoming light to form an image at the focuser.
In the past, I have written about my thoughts on using a refractor for astrophotography and that I think it is the best choice to get started in deep-sky astrophotography.
Modern refractors are commonly described as achromatic or apochromatic, with ED doublets and triplets offering different levels of color correction. Chromatic aberration appears as false-color fringing because different wavelengths do not all reach the same focus.
The William Optics RedCat 61 is an excellent refractor telescope for astrophotography.
This happens when the objective cannot bring every wavelength of visible light to the same focal plane.
There are several ways to reduce chromatic aberration. Designers can combine lens elements made from different glass types or use a longer focal ratio to reduce visible color fringing.
Apochromatic refractors (apochromat) have objectives built with special, extra-low dispersion materials. They are designed to bring three wavelengths (typically red, green, and blue) into focus in the same plane. The residual color error (tertiary spectrum) can be down to an order of magnitude less than that of an achromatic lens.
Such telescopes contain elements of fluorite or special, extra-low dispersion (ED) glass in the objective and produce a very crisp image that is virtually free of chromatic aberration. Due to the special materials needed in the fabrication, apochromatic refractors are usually more expensive than telescopes of other types with a comparable aperture.
Advantages of Refractor Telescopes
Refractor telescopes are mechanically reliable, and apochromatic models can reduce chromatic aberration to a very low level. Their optical systems are also more resistant to misalignment than those of most reflector telescopes.
The closed tube protects the interior optics from dust, reducing routine maintenance. The exposed front objective can still collect pollen, fingerprints, and dew, so it should be capped when not in use and cleaned only when necessary.
High-quality refractors can also provide crisp, high-contrast images with high magnification, making refractors a great telescope for astrophotography and planetary/lunar observing.
They are usually much smaller and more portable than other types of telescopes too. This means that you will not require a large equatorial telescope mount as you would for some of the larger telescope types.
The Sky-Watcher Esprit 100 ED APO.
Some of my favorite refracting telescopes I have used:
A refractor telescope is my top choice when it comes to your first astrophotography telescope. The compact size, crisp optics, and wide-field imaging possibilities are perfect for newcomers.
Downsides of a Refractor Telescope:
Although refractor telescopes are portable, durable, and relatively low maintenance, they have a few downsides to consider:
- Chromatic Aberration: Achromatic refractors can produce purple fringing or halos around bright objects because different colors do not reach the same focus.
- Limited Aperture: Large refractor objectives become heavy and expensive quickly, so affordable models usually have less aperture than reflectors. Their actual field of view depends on focal length and eyepiece or camera sensor size.
- Expensive: High-quality refractor telescopes can be quite expensive, especially when compared to reflector telescopes of the same aperture.
An apochromatic objective reduces chromatic aberration, while a matched field flattener corrects field curvature near the corners of an astrophotograph. These accessories solve different optical problems.
Reflector Telescopes
Unlike a refractor, a reflector telescope uses a curved primary mirror to collect and focus light. In a Newtonian reflector, a small flat secondary mirror near the top of the tube redirects the focused light into an eyepiece or camera at the side.
A reflector telescope often provides the best value because it offers more aperture for your money. A 6-inch refractor is generally much more expensive and heavier than a 6-inch Newtonian reflector.
Related Article: How Much Does a Telescope Cost?
Many reflecting telescopes are great for viewing planets such as Mars, Jupiter, and Saturn. Their relatively simple optical design makes them economical to manufacture in larger apertures.
The most common form of this telescope is the Newtonian reflector, which was (you guessed it) invented by Isaac Newton.
A Newtonian reflector includes a curved, dish-shaped primary mirror to collect light at the bottom of the telescope. At the top of the telescope, a small diagonal secondary mirror directs the light from the primary mirror to the eyepiece, found on the side of the telescope.
Setting up my Newtonian Reflector telescope on a Dobsonian mount.
Using a mirror instead of an objective lens avoids the chromatic aberration produced when glass bends different wavelengths by different amounts.
The objective mirror on a reflector is supported at the back end of the telescope, so the mirror can be made very large. Compared to a refractor of the same size, a reflector telescope is cheaper to make and can therefore be cheaper to purchase.
I consider a Dobsonian-mounted Newtonian to be the best telescope for many beginners. It offers a large aperture, a stable and practical format for visual observing, and an affordable price tag. Familiar examples include the Apertura AD8, Sky-Watcher Dobsonians, and the classic Orion SkyQuest series.
Newtonian reflectors commonly operate at focal ratios from f/4 to f/8. Shorter-focal-length models can provide wide views, while longer models are often easier to collimate precisely and place less demand on eyepieces.
A few disadvantages are that the mirrors can shift out of alignment, especially after transport, and the open tube allows dust to reach the optics. Collimation should be checked periodically, but mirrors should only be cleaned when contamination is affecting performance.
The secondary mirror slightly reduces contrast, while the thin spider vanes that support it create diffraction spikes around bright stars.
Reflecting telescopes I have used:
My Apertura CarbonStar 200 Reflector Telescope
What is Collimation?
In general, reflector telescopes require more upkeep than refractors. Their collimation should be checked regularly so the mirrors remain aligned for the best possible image.
The process of collimating a reflector telescope involves precisely aligning the mirrors in the telescope using specialized, simple tools. A laser collimator is a handy tool to consider purchasing if you own a reflector telescope.
The diagram below displays what you see through a collimating eyepiece down a reflector’s focuser tube.
How to Collimate Your Newtonian Reflector Telescope (Sky and Telescope).
Ritchey-Chrétien Telescopes
Ritchey-Chrétien telescopes (RCs) use hyperbolic primary and secondary mirrors to bring an image into focus. Because the design uses mirrors without a front corrector lens, an RC is a reflector rather than a catadioptric telescope.
RCs are well suited to long-focal-length astrophotography of distant, small objects in the night sky. The Hubble Space Telescope uses a Ritchey-Chrétien Cassegrain design.
The iOptron Photron RC6 (Ritchey-Chrétien).
The secondary mirror in a Ritchey-Chrétien is held by spider vanes, much like a Newtonian telescope. These create diffraction spikes around bright stars in an astrophoto, an effect many astrophotographers enjoy.
The Ritchey-Chrétien design corrects coma and spherical aberration, and its mirror-only optics do not produce chromatic aberration. It can still show field curvature and off-axis astigmatism, which is why many imaging systems use a field flattener.
In late 2018, I had an opportunity to test my first Ritchey-Chrétien telescope, the iOptron Photron RC6.
Catadioptric Telescopes
A catadioptric, or compound, telescope uses both lenses and mirrors. Its folded optical path provides a long effective focal length in a relatively short, portable tube.
The result is a large-aperture, long-focal-length telescope that is easier to transport than a Newtonian with a similar focal length. Schmidt-Cassegrains may need occasional collimation, particularly after rough transport, although mine have held alignment well.
The image below shows an 11-inch Schmidt-Cassegrain telescope with a native focal length of 2800mm at F/10. Thanks to its large aperture and useful image scale, this is the telescope I use to photograph planets in impressive detail.
Looking through my Celestron NexStar 8SE telescope
Similar to refractors, these telescopes have closed tubes that help keep dirt and dust away from the interior optics.
The exposed corrector plate is prone to dew. A dew shield slows moisture buildup, while an active dew heater may be necessary on humid nights.
A Schmidt-Cassegrain, such as a Celestron C8 or C11, combines a Cassegrain-style folded light path with a Schmidt corrector plate. Celestron and Meade are the two brands historically most associated with mass-market Schmidt-Cassegrain telescopes.
Catadioptric telescopes I have used:
Another catadioptric telescope widely used for astronomy is the Maksutov-Cassegrain, or “Mak” for short. Its corrector and mirrors provide strong correction in a compact design, although no practical telescope is completely free of optical aberrations.
These telescopes are great for lunar and planetary viewing, as well as terrestrial daytime use. Their long focal lengths produce a narrower field of view, and their slower focal ratios generally require longer exposures for deep-sky imaging than a faster system.
A well-known “Mak-Cass” is the Celestron NexStar 4SE. It combines a 4-inch (102mm) Maksutov-Cassegrain optical tube with a compact computerized GoTo mount.
The Celestron NexStar 4SE Maksutov-Cassegrain Telescope.
Newtonian vs. Cassegrain Telescopes
A Newtonian reflector offers the most aperture for the money and can provide a wide field at a moderate focal length, but its tube becomes physically larger as focal length increases. Cassegrain-family designs fold the light path between two mirrors, creating a much shorter tube with the eyepiece at the back. Schmidt-Cassegrains and Maksutov-Cassegrains add a front corrector and are catadioptric; a Ritchey-Chrétien is a mirror-only Cassegrain reflector.
For visual deep-sky observing on a budget, a Newtonian or Dobsonian is usually the better value. For planets, small galaxies, or a portable long-focal-length setup, a Cassegrain design can be more practical. The trade-offs are a larger central obstruction, more cool-down time, greater dew sensitivity in corrected designs, and a higher price per inch of aperture.
Astrophotography
If deep-sky astrophotography is your goal, choosing the right telescope will depend on the types of objects you wish to shoot. I have put together a list of 10 of the best astrophotography telescopes available, all with example images I have taken with them myself.
A high-quality triplet apochromatic refractor is a great choice for large nebulae, open clusters, and broad galaxies such as Andromeda. A long-focal-length SCT is a better fit for small galaxies and planetary astrophotography.
Because the moon is large and bright, almost any telescope is suitable for photographing it. Photographing fainter objects such as comets, nebulae, star clusters, and galaxies is more demanding. For long-exposure deep-sky work, mount tracking accuracy is usually more important than the optical design alone.
To capture images of space through a telescope, you must attach a camera to the telescope using the appropriate adapters.
You can also handhold your camera up the eyepiece of your telescope to take a picture of the moon or bright planets, but this method can be challenging and yield poor results.
A typical astrophotography camera and telescope setup (Askar SQA106)
Most of my deep-sky images were captured with apochromatic refractors. The camera was threaded directly onto the focuser drawtube of the optical tube assembly at prime focus, using the instrument’s native focal length.
No single telescope is ideal for every target. Large nebulae need a wide field, while planets and small galaxies benefit from more image scale.
The Crescent Nebula captured from my backyard
Smart Telescopes
Smart telescopes like the ZWO Seestar S50 are now a popular entry point into amateur astronomy. They do not offer the classic visual experience of looking through an eyepiece, but they can automatically locate, track, and stack images of night-sky objects.
They work similarly to an astrophotography setup, where an astronomy camera collects exposures through a small refractor telescope. The integrated app displays and processes the result on a smartphone or tablet.
The Seestar S50 is an all-in-one ‘smart telescope’ that produces images of space on your smartphone.
Smart telescopes are increasingly popular because they allow the user to easily find and photograph deep-sky objects without any prior knowledge of the night sky. They are a big hit at astronomy outreach events because multiple people can enjoy views of space at once without the lineup at the eyepiece.
Related Article: Dwarf 3 Smart Telescope Review
The Bottom Line
The best type of telescope for you depends on what you want to observe, where you will use it, and how much equipment you are willing to transport. If you want a simple and rewarding visual experience, an 8-inch Dobsonian reflector is probably your best bet.
If you’re an amateur astrophotographer like me, a compact, wide-field apochromatic refractor will likely be your most valued telescope. The optical design affects the telescope’s physical size, focal length, field of view, maintenance needs, and cost, while the eyepiece determines visual magnification.
Because these aspects change based on design, there is no “one-size-fits-all” telescope for every scenario. You may even find that a simple pair of binoculars you own is a great fit for astronomy.
With that being said, many seasoned amateur astronomers recommend having a dedicated telescope for visual astronomy (one that is easy to transport and offers comfortable views), and one strictly used for astrophotography.
About Me:
Trevor Jones and his wife Ashley.
I have been observing and photographing the night sky using various telescopes for more than 15 years. The largest telescope I have ever observed through was a 36-inch Dobsonian reflector at the Cherry Springs Star Party in 2018!
Helpful Resources:
- What to Consider When Buying a Telescope
- How to Choose a Telescope (Sky & Telescope)
- How to Choose Your Telescope’s Magnification (Sky and Telescope)
